"Richard J." wrote in message
...

There is a small offset, primarily because the stairs down to the
platform are very near the northbound face, which means that the TV
monitors have to be south of the stairs. But the southern extension of
the northbound platform is longer than needed to compensate for this,
and most of it is not required for a 6-car D-stock train. Silverlink
Metro (NLL) trains are generally (always?) shorter.

Silverlink NLL trains are always 3-car 313s. Anything longer wouldn't fit
into the platform at Willesden HL (even when a stone train isn't derailed
there).
Peter